1. Field of the Invention
The present invention relates to a wireless communication, and more particularly, to an internal antenna of a wireless communication terminal in which internal style folded monopole antenna is installed.
2. Description of the Related Art
As wireless communication technologies are developed, communication terminals using handsets, wireless personal digital assistants (PDA), and wireless LAN are developed, and antennas employed in the respective terminals are main parts to give influence to the wireless communication performance of the communication terminals.
An external dipole antenna and a helical antenna are widely used as conventional antennas, employed in conventional wireless communication terminals. However, the external antenna has shortcomings such that the characteristics of the external antenna may be deformed by a user, the external antenna may give bad influence to design the wireless communication terminals, and since the external antenna is mounted to the outside of the wireless communication terminals, the wireless communication terminal cannot have aesthetic pleasing appearance.
In order to overcome the shortcomings, internal antennas are inevitable. For example, internal antennas for wireless LAN are employed in laptop computers, smart displays, Internet refrigerators, or the like having weak interference in a space and weak influence from ground of adjacent circuits and a case of the wireless communication terminals. However, since portable communication terminals such as a handset, a wireless personal digital assistant, or the like, has a very small space, it is difficult to apply the internal antennas to the portable communication terminals.
What has been employed in the handset is a planar inverted F-antenna (PIFA), and the wireless personal digital assistants are employing a ceramic chip antenna and the planar inverted F-antenna.
However, since the planar inverted F-antenna has narrow bandwidth, radiation efficiency of the planar inverted F-antenna is reduced due to reflective loss of an input terminal, and since resonance characteristics is appeared at the length of a quarter-wavelength, the length of the planar inverted F-antenna must be increased.
Moreover, since the ceramic chip antenna employed in the wireless personal digital assistants uses high dielectric material, the radiation efficiency of the ceramic chip antenna is decreased.